With the development of telecommunication technologies and wide-spreading of telecommunication equipment, recently, terminals having various operation functions such as a desktop computer, a laptop, a smart phone, a smart pad, and so on are used over almost fields in living, and data, which are already produced or acquired and thus stored in the terminals, or data (video data, voice data, etc.), which can be acquired in real time through the terminals, is transferred whenever and wherever to other terminals through communication network like internet network, thereby improving the conveniences in work.
However, hacking technologies, which use the conveniences for a bad purpose, that is, which are accessed illegally to the data recorded in another person's terminal or acquired through his or her terminal to use the data for a bad purpose, are also developed, and accordingly, security technologies for protecting the data of the terminals from hacking are rapidly developed and suggested.
Through the security technologies, however, the security is not perfectly achieved, and so as to basically prevent the illegal use of data, accordingly, an offline terminal having no communication connection and an online terminal having communication connection are all used. Only in case where data transfer to the outside is needed, the online terminal is used, and the other work is performed in the offline terminal. The data of the offline terminal is transferred to the online terminal only through portable memory means like a USB memory, and whenever the data transfer is performed, accordingly, the USB memory should be moved, thereby causing many inconveniences in use.
Accordingly, the plurality of terminals should be provided to undesirably occupy large space, and so as to solve the above-mentioned problem, a desktop computer technology is disclosed in Korean Utility Model Registration No. 20-0288715 wherein an interior of a main body is divided into two sections where two boards separated functionally are provided to enhance space utilization, a KVM switch is used to commonly use a monitor, a keyboard and so on, and connection to external internet network and connection to internal administrative network requiring security are concurrently performed in real time by means of one desktop computer.
According to the conventional technology, however, USB ports as means for transferring materials between the plurality of boards are provided on the respective boards, and so as to perform data transfer, in this case, the two boards are necessarily connected to each other by means of the USB ports, so that in the connection state of the two boards, the data in the two boards can be all hacked through external internet network, thereby still causing a weakness in security.